Ritz on the Optics of Moving Bodies.

Robert S. Fritzius - Shade Tree Physics

Installed 1 Oct 1998 - Latest Update 11 Dec 2011

Walter Ritz's preliminary statements related to the optics
of moving bodies versus his long-term intentions may have
been confused. (1)(2)

In his article "Recherches critiques sur l'Électrodynamique Générale"
Ritz said: [English translation] "The velocity of light then depends on that
possessed by the body which emits it at the instant of emission. From that
instant, the velocity of the particles remains invariable, no matter what the
subsequent motion of P is, even when the particles pass through ponderable
bodies or electric charges. I said in the Introduction that this hypothesis,
which is demanded by the superposition principle, is only temporary; and is
contrary to that of action and reaction. But the advantage of being as close
as possible to the corresponding hypotheses of Lorentz makes it
preferable for the goal that I intend here."
(3) pp.211, 212

This following excerpt of his further comments on the subject (with an
English translation) shows that Ritz seems to have seen the need for
some kind of environmental influence on his fictitious particles on
the order of Tolman's extinction theorem or that of Ewald and Oseen.
The French text on the left below is from Gesammelte Werke
Walther Ritz Oeuvres, pp 443-444, published by the Société
suisse de Physique, Gauthier-Villars, Paris, 1911. The original article
was "Recherches Critiques sur les Theories Electrodynamiques de Cl.
Maxwell et de H.-A. Lorentz," published in Archives des Sciences
physiques et naturelles, 36, 209, 1908.

English

The principle of relativity of motion, in it's classical form,
demands that the waves emitted by a uniformly moving system be free
from all sensible external influences. They move with the system in a
manner in which the center of each spherical wave continues to coincide
with the electron which emitted it, and in which the radial velocity is
universal and equal to c. If the motion of the electron is
variable, then the principle of relativity no longer determines the
velocity with which the center of the wave is displaced; however, this
velocity must be constant (otherwise there would be action at a
distance between the electron and the emitted wave). True, it will no
longer be possible to conserve the image of "ether" or "waves in an
elastic body " for this law of propagation; but, should we choose to
conserve it, and with it the partial differential equations, it would be
necessary to add the new Lorentz-Einstein transformation hypothesis
which, to tell the truth, profoundly changes the conditions of the problem,
[so much so] that the image of "ether" or the "elastic body" becomes
entirely inapplicable. In addition, in the views of Lorentz and Einstein,
the propagation of light is no longer compatible with the mechanical
image at all. On the contrary, the law of propagation which we have
described above corresponds simply to the image of particles emitted in
all directions with the same radial speed, and which continue to move
uniformly. It therefore draws closer to coming into rapport
with Newton's emanative theory. I have shown (loc. cit., 2nd
part) that, supposing this law is true, whatever the motion of
the electron, and admitting that the fictitious particles act on the
electric charges with which they come into contact, we aren't penalized
in any manner to construct an infinity of electrodynamic theories
in perfect accord with experiment, save in that which concerns the
optics of moving bodies. Here, experience, as interpreted from the
atomic conception of electricity, which we have adopted up to
now, states the result uniquely and simply (1): When a light ray
sets into vibration the electric charges of a medium which in their turn emit
new waves, the centers of these waves move, not with the velocity of the
medium (like that wanted by our hypothesis) but with the velocity
of the source of light. However, this is what the principle of action and of
reaction permits us to specify/predict. Indeed, that principle is injured by our
hypothesis, seeing as the action of our fictitious
particles (because of our use of this image) on the ions doesn't correspond
to any reaction of the ions on the particles. It is necessary, as in
Lorentz's theory, to attribute a momentum to the radiant energy, which is
much more natural when we consider the energy as projected than
when we consider it as propagated; and the initial velocities of the
fictitious particles emitted by an ion are determined by the
conservation of momentum principle or the principle of reaction. In
the case of optics, all radiant energy is provided by the
source, and the screen of our optical apparatus doesn't furnish any
portion. It is therefore natural to think that the principle of reaction,
however precisely stated, will have for a result that the velocity of the
fictitious particles emitted by the ions of the screens, etc., are uniquely
determined by that of the light source.

Ritz's phrase "comme le voulait notre hypothése" / "like that wanted by our hypothesis" [which Fox omits in his quote] suggests that Ritz did, in fact, desire a model in which the centers of the new waves move at the speed of light with respect to their secondary radiation sources.